The Prolost Store runs on an e-commerce platform called Gumroad. According to Gumroad's help article on the subject, VAT regulations require digital marketplaces such as theirs to collect VAT. Gumroad is the entity with which you are doing business, so they are responsible for collecting VAT, not Prolost.

If you do not have to pay VAT, Gumroad says you may request a VAT credit directly from them.